Anatomy of cast glass: The effect of casting parameters on the meso-level structure and macro-level structural performance of cast glass components

Cast glass has great application potential in the architectural realm, yet, despite its possibilities and attractiveness, designers, engineers and developers are, from an early design stage, hesitant to employ it; the limited available and craft-based manufacturing facilities, the questionable quality of the product, the missing engineering data and quality control processes and the uncertainties linked with the structural application of cast glass, lead to discouraging high cost/ high risk solutions. Within the listed challenges and uncertainties, perhaps the most striking is our inability to answer the most obvious question: what is the strength of cast glass? A simple answer to this question does not exist, as the mechanical properties of cast glass vary from product to product, and are directly influenced by the employed chemical composition, thermal history, and casting process. Adding to this complexity, further questions over the mechanical properties and quality arise, once waste (contaminated) glass cullet and lower processing temperatures are used, in the efforts of reducing the environmental impact of cast glass components.

Focusing on this knowledge gap, the aim of this work is to develop an understanding of the effect of the casting parameters on the meso-level structure of cast glass, and thereupon of the relationship between this meso-level structure and the strength, stiffness and fracture resistance of cast glass components. Towards this aim, the dissertation adopts an experimental approach based on physical prototyping by kiln-casting, and destructive and non-destructive testing. The experimental work shows that by kiln-casting, a larger variety of chemical compositions can be cast, even at relatively low processing temperatures. As a consequence, a broad range of mechanical properties arises, especially when waste cullet is employed. Based on the casting parameters, combinations of different defects, grouped in meso-level structures, are commonly found in cast glass, yet these can often be tolerable when situated in the glass bulk. The dissertation highlights the potential of recycling-by-casting of currently challenging to recycle glass waste into reliable and aesthetically unique structural components, and the advantages of engineering composite cast glasses. It also underlines the need for manufacturing guidelines, test data, product certifications and quality control protocols, for the successful implementation of cast glass in the built environment.